MGM 120 -- Feigao 8s Melted Spur gears

[Z06jim]

Well after playing around with some Mamba based small Brushless in my Evader BX, I looked around and found this place.
BX all possible Alum.
Slammed for street runnng ~1/2" ground clearance

Last week I order the MGM 120, Feigao 8S, and motor clamp.
All arrived this afternoon and after a couple of hours installed for first runs.

Started on 6 cell GP3200
21/81 pinion/spur
Ran about like I expected
Could hold my hand on the motor as long as I wanted and the controller was barely warm.
Spreadsheet says about 32mph

Changed over to 3S Lipo (3200 FMA/Kokam) and quite a change.
Same gears
Insane speed
Stopped after about 4 Min to check temperatures
Hot, but could hold motor for 5-7 sec.
Controller still barely warm
Battery cool
Spreadsheet says 49.9 mph

1 more minute run spur gear goes rolling down the street!!!

Anyone know of a more heat resistant spur gear, 48p 78 or 81 tooth?
Slipped was set pretty tight, would not slip till it got up about 45 deg while holding both rear tires between my knees.